Investigation of the Mechanism of Fulminant and Severe Hepatitis Correlated with Hepatitis B Virus Mutations

B型肝炎病毒感染可导致广泛的肝损伤，包括自限性急性肝炎、暴发性肝炎和慢性肝炎进展为肝硬化或急性加重为肝功能衰竭，以及非对称性慢性携带状态。B型肝炎核心抗原可能是细胞毒性T淋巴细胞（CTL）的免疫靶点。为了研究为什么会发生严重的免疫攻击，对整个前核心区和核心区进行了测序。所有无症状健康携带者和自限性急性肝炎患者的推导氨基酸残基均无明显变化。而慢性重型肝病和重型肝炎患者的小片段氨基酸呈聚集性变化。这些结果表明，这些突变区域可能在B肝炎病毒疾病的发病机制中起重要作用，这些突变与严重的肝损害有关。最近的研究表明，与I类人淋巴细胞抗原（HLA）结合的内源性加工病毒肽可被CTL识别，加工病毒肽的大小可小至9个氨基酸。为了研究CTL识别HBV多肽与HLA I类分子结合的机制，我们已经建立了一种利用亲和柱层析从肝细胞中分离HLA I类分子的方法。我们已经开始分析从纯化的HLA I类分子洗脱的此类肽。

Hepatitis B virus infection leads to a wide spectrum of liver injury, including self-limited acute hepatitis, fulminant hepatitis and chronic hepatitis with progression to cirrhosis or acute exacerbation to liver failure, as well as asymtomatic chronic carrier state. The hepatitis B core antigen could be an immunological target of cytotoxic T lymphocytes (CTL). To investigate the reason why the severe immunological attack occurs, the entire precore and core region was sequenced. No significant change in deduced amino acid residuewas noted in all the asymptomatic healthy carrires and all the self-limited acute hepatitis patients. In contrast, clustering changes in small segments of amino acids were found in all the patients with severe chronic liver disease and the fatal hepatitis cases. These data suggest that these regions with mutation may play an important role in the pathogenesis of hepatitis B viral disease, and such mutations are related to severe liver damage.Recent studies revealed that the endogenously processed viral peptides bound to the class I human lymphocyte antigen (HLA) are recognized by CTLs and the size of the processed viral peptide could be as small as 9 amino acids. To study the mechanism how CTLs recognize HBV peptides bound to HLA Class I molecules, we have already established a method to separate HLA Class I molecules from hepatocytes using an affinity colum chromatography. We have started to analyze such peptides eluted from purified HLA class I molecules.